Outcomes in Patients Presenting with Symptoms Suggestive of Acute Coronary Syndrome with Elevated Cardiac Troponin but Non-obstructive Coronary Disease on Angiography

Background Many patients provisionally diagnosed with acute myocardial infarction (AMI) have angiographically unobstructed coronary arteries. Despite other potential causes, patients are often diagnosed as AMI with psychosocial implications and medication burden. The aim of this audit was to review such patients at our centre. Methods All patients investigated for possible AMI with coronary angiography from 2007 until 2011 at Christchurch Hospital, New Zealand, in whom cardiac troponin was elevated (with no other cause found for that elevation) but coronary angiography showed diameter stenosis <50% were reviewed. Primary outcome was two-year cardiac death and AMI (by universal definition). Results Of the 351/6493 (5.4%) who met the inclusion criteria, 180 had normal angiograms and 171 had non-obstructive coronary disease (stenosis >0% and <50%). By two years there were two cardiac deaths (0.6%) and five AMIs (1.4%). The primary outcome rate was therefore 2.0% (2.2% for those with normal angiograms and 1.8% with non-flow limiting coronary disease, p=1.000). Conclusion Patients who have presented with AMI symptoms, elevated cardiac troponin, and unobstructed coronary arteries on angiography are at very low risk of cardiac death (0.6%), AMI (1.4%) or either (2.0%) at two-year follow-up.